The present invention relates to a process for determining the level of molten metal in a metallurgical vessel, the temperature of the molten level and the extent of wear of the refractory lining of the vessel. The present invention also relates to a metallurgical vessel or container including structure for determining the molten metal level, the molten metal temperature and the degree of wear of the refractory lining of the vessel.
With increases automation it is becoming more important to develop a system for monitoring the level of molten metal in metallurgical vessels and containers. Also, it is necessary to constantly control the temperature of the molten metal within such containers and to control the extent of wear or erosion of the refractory lining of such a metallurgical container. Such controls of course depend upon being able to measure such temperature and extent of wear.
With respect to determining the level of molten metal in a metallurgical container, for example a transfer ladle in a steel mill, it conventionally is necessary to attempt to visually observe such container so that it does not become overfull of spill over.
For metallurgical reasons, it is desirable that during a continuous casting operation the molten metal, for example molten steel, be cast without coming in contact with the surrounding air, that is that such system be closed. At the same time however, it is necessary that the level inside the casting tundish remain constant. The precondition for achieving such results is a continuous measuring of the level of the molten steel within the tundish.
In a transfer ladle or in an LD converter, a gross weight measurement to determine the level of the molten metal inside the ladle or converter frequently is not sufficiently accurate because the weight of the fireproof refractory lining changes during operation due to erosion and wear.
The problem of measuring the molten metal level is conditionally simplified if it is necessary to determine only upper and lower limits for the level, that is if the level has to be maintained below a certain level or between two levels.
In order to avoid rupture of a metallurgical container, it is important to constantly monitor temperatures within the container and wear or erosion of the fireproof refractory lining of the container.
A number of techniques are known to measure the level of a liquid. It is also known that electrically conducting liquids can serve to electrically connect contacts, whereby it is possible to determine from the electrical resistance between two electrodes whether the liquid level is below or above an upper electrode. However, all known electrodes will fail during continuous operation with materials that have high melting points, particularly steel. Thus, metal electrodes form alloys and melt. Electrodes made from graphite bars dissolve.